1. Field of the Invention
The present invention relates to a semiconductor package and a method for manufacturing the same, and more particularly to a plastic semiconductor package and a method for manufacturing the same wherein bumps are constructed such that the semiconductor package can be lightened, thinned and miniaturized to be densely surface-mounted on a printed circuit board.
2. Description of the Prior Art
Referring to FIG. 1, there is shown a conventional plastic semiconductor package. As illustrated in the drawing, the plastic semiconductor package comprises a semiconductor chip 1, a lead frame 2 including a lead frame pad 2a on which the semiconductor package chip 1 is attached, a plurality of inner leads 2b wire-bonded to the semiconductor chip 1 and outer leads 2c extended from the outer leads 2c, a plurality of metal wires 3 for electrically connecting the inner leads 2b of the lead frame 2 to the semiconductor chip 1, and mold resin 4 for enveloping a certain area occupied by the wire-bonded semiconductor chip 1 and the inner leads 2b of the lead frame 2 to form a package body.
The semiconductor chip 1 is fixedly attached to the pad 2a of the lead frame 2 by epoxy adhesive 5. The package body is made of the mold resin 4 by using transfer molding.
A method for manufacturing the above-constructed conventional plastic package comprises, a die attaching step of attaching the semiconductor chip 1 separated from a wafer to the pad 2a of the lead frame 2 by using epoxy adhesive 5, a wire-bonding step of electrically connecting the die attached semiconductor chip 1 to the inner leads 2b of the lead frame 2 by means of the metal wires 3, a molding step of forming the package body by molding mold resin to envelope an area occupied by the wire-bonded semiconductor chip and the inner leads 2b, and a trimming/forming step of cutting dam bars connected to outer ends of the lead frame 2 to provide a separate semiconductor package and bending the cut outer leads 2c of the semiconductor package into required shapes.
However, the plastic semiconductor package produced by the above-mentioned method has disadvantages in that since an area occupied by a single package is increased because of presences of the outer leads 2c outward protruded from both sides of the mold resin 4 and metal wires 3 for electrically connecting the semiconductor chip 1 to the inner leads 2b, rate of area occupied by the package on a primed circuit board (not shown) is increased.
Also, since the conventional outer leads 2c of the lead frame 2 frequently undergoes poor bending and poor contact, accuracy of test for electrical property is deteriorated. In addition, the package susceptible to be broken and delaminated between surfaces due to difference of thermal expansion coefficient between the semiconductor chip 1 and the die pad 2a.
Furthermore, the conventional method for manufacturing a semiconductor package has disadvantages in that since gaps are formed between leads due to mechanical stress during the trimming/forming step, moisture is penetrated therebetween, thereby causing the package to deteriorate. Also, since the method must pass through various complicated steps, productivity is decreased and manufacturing cost is increased.